Question: If $a + b = 2$ and $x + y = 5$, what is $3y + 3x + 5a + 5b$ ?
$= 5a + 5b + 3x + 3y$ $= (5) \cdot (a + b) + (3) \cdot (x + y)$ $= (5) \cdot (2) + (3) \cdot (5)$ $= 10 + 15$ $= 25$